An emulsion is a composition containing a stable mixture of two immiscible phases, in which droplets of one phase are dispersed throughout the other phase. A typical example of an emulsion is a water-in-oil (W/O) emulsion wherein a certain content of water in a form of water droplets is uniformly dispersed throughout a lipid content that forms a continuous lipid phase. For instance, WO 2014/066632 discloses lipid-based W/O emulsions wherein the lipid content may vary from 1 to 99 wt %, Lipids may include waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, fats and others. Examples of lipids suitable for use in the W/O emulsions of WO 2014/066632 include vegetable or animal derived oils.
W/O emulsions where the lipid is a fat are typically used to manufacture various food products such as spreads, e.g. margarine. W/O emulsions can also be used as a precursor to prepare water-in-oil-in-water (W/O/W) or oil-in-water-in-oil (O/W/O) emulsions, which in turn may be used to make food products containing thereof, such as mayonnaise and dressings. For low fat W/O emulsions, i.e emulsions having an increased amount of water, the stability thereof may become problematic especially when the fat content drops below 60 wt % and particularly below 40 wt %. Food products containing low-fat W/O emulsions may be deleteriously affected by the emulsion's instability, e.g. experiencing flocculation, creaming, coalescence, and/or Ostwald ripening, which in turn may negatively influence their aspect, quality and/or mouthfeel behaviour. In order to stabilize low-fat W/O emulsions a number of strategies were developed.
One method to stabilize a low-fat W/O emulsion is to use special solid fat compositions as the fat phase thereof. EP 1 492 410; WO 2011/108919; and WO 2014/005797 contain disclosures of various solid fat mixtures used to stabilize low-fat W/O emulsions. However, solid fats typically contain an increased concentration of saturated fatty acids (SAFA) which are considered non-healthy as they are a known risk factor for cardiovascular health.
Another method to stabilize low-fat W/O emulsions is with the help of emulsifiers; and many effective emulsifiers are known such as esters of fatty acids, salts of fatty acids, lactylates, glycerol esters, polyglycereol esters of fatty acids, polyglycerol esters of polycondensed fatty acids of castor oil, fatty acid monoglycerides, fatty acid diglycerides, acetylated monoglycerides, calcium stearoyl dilaciate and lecithin. However, for achieving optimum stability in low-fat W/O emulsions, powerful emulsifiers need to be used in order to compensate for the reduced fat content (and hence increased water content). One of the few known emulsifiers able to effectively stabilize a low-fat W/O emulsion is polyglycerol polyricinoleate (PGPR), typically used in combination with a monoglyceride, a diglyceride and/or lecithin. EP-A-968,655; EP-B-1343384 and US2009/0029025 disclose for example low-fat W/O emulsions stabilized with PGPR. The use of PGPR (identified as E476) and mono- or di-glycerides (identified as E471) may bring however a number of disadvantages. The low-fat W/O emulsions containing such powerful emulsifiers are so stable that their melting behaviour is affected. In particular their mouth-melting behaviour, i.e. the melting behaviour in the mouth, may be affected which in turn may affect the mouthfeel sensation of products containing thereof. Also, the water droplets dispersed throughout the fat phase of the W/O emulsion, which usually carry flavours or taste-enhancing components, may not effectively break in the mouth, influencing therefore the taste of a product containing such emulsion. The replacement of such emulsifiers in low-fat W/O emulsions with emulsifiers which help avoiding these problems may therefore bring a number of benefits such as optimal demulsification in the mouth and may enable the removal of E476 andE 471 from labelling.
Another method to stabilize an emulsion is known from WO 2013/003670, which utilizes an emulsifier composition comprising a blend of a lecithin and an additional emulsifier. However, the emulsifier composition of this publication may lack the emulsification power which makes it optimal for being used in producing a W/O emulsion, in particular a low-fat W/O emulsion.
Edible W/O emulsions used as dairy product substitutes are also known from EP 0 997 074 and EP 0 997 075, said emulsions utilizing an emulsifier comprising an alcohol-insoluble fraction of vegetable lecithin. M. Akhtar et al. (Food Colloids—Fundamentals of Formulation, ISBN 0-85404-850-2) also use a de-oiled fractionated lecithin which was phosphatidylcholine depleted to make W/O and W/O/W emulsions. The inventors observed that the properties of these known emulsions may be further improved.
Other methods to stabilise W/O emulsions include the use of polysaccharides such as hydro-colloids, e.g. starch, alginate, pectin, xanthan and carrageenan. However, with decreasing the fat content, these methods become increasingly ineffective in preventing phase separation and creaming, i.e. release of water during mechanical manipulation thereof, e.g. during spreading.
An object of the present invention may therefore be to provide a low-fat W/O emulsion which is the least possible affected by the above mentioned problems. A particular aim of the present invention may also be to provide a low-fat W/O emulsion having optimum stability at low and ambient temperatures. A more particular aim of the present invention may be to provide a low-fat W/O emulsion which spreads easily and shows good organoleptic properties.